The present invention relates to a semiconductor device and a method for fabricating the same, and particularly relates to a semiconductor device whose transistor characteristics can be improved by filling respective isolation regions formed in the semiconductor substrate with different materials and a method for forming filled-in regions locally having different stresses.
In recent years, as semiconductor integrated circuits have been increasing in packaging density, functionality and speed, there has been a proposed technique in which stress is applied to the channel of a transistor by a stressor film so as to increase the driving force thereof. For example, if a high stressor film is used as a liner film, it is possible to increase stress that is applied to the channel.
The direction of stress for increasing driving force of an N-channel MIS transistor is opposite to the direction of stress for increasing driving force of a P-channel MIS transistor. In view of this, a method was proposed in which different stress liner films are formed on transistors of different conductivity types (see, for example, H. S. Yang. et al. IEDM 2004, p 1075).
FIG. 14 is a cross-sectional view illustrating the structure of a conventional semiconductor device. In the semiconductor device illustrated in FIG. 14, an N-channel MIS transistor NTr and a P-channel MIS transistor PTr are arranged. A liner film 103 having tensile stress is formed on a gate electrode 101 and a doped layer 102 in the N-channel MIS transistor NTr, while a liner film 113 having compressive stress is formed on a gate electrode 111 and a doped layer 112 in the P-channel MIS transistor PTr.